[GRASS-user] use r.sun with monthly cloud cover data

[Simone Ruzza]

Dear GRASS users,

I  would like to use the r.sun module to produce a map of montly solar
radiation for a certain area. I would like to incorporate cloud cover
data into the calculations, as well as information on local topography
(i.e. aspect and slope). I was wondering whether you could help me to
solve two problems: i) I have not quite yet understood what I should
do to specify a raster containing data on cloudiness when using the
module
eg. r.sun elevin=altmap aspin=aspmap slopein=slopemap + cloudmap?? ii)
 I am interested in a montly average of daily sum of solar radiation,
and I only have montly cloud cover data.  I suspect that this is not
ideal when calculations by r.sun are done on daily basis. Do you
confirm? Is there a way around this?

thanks in advance,

Simone